Disposable filter cartridges are widely used for the filtration of a variety of fluids. Generally, such filter cartridges include a cylindrically shaped filter medium which define a central core chamber. The filter medium is typically provided with appropriate end caps which allow fluid to be forced through the depth of the filter media. Some filter cartridges (e.g., as depicted in FIG. 4 of U.S. Pat. No. 5,681,469) are provided with an integral rigid core structure which provides the filter media with structural support (e.g., so the filter medium is capable of withstanding fluid pressure differentials during use). Other filter cartridges, as shown, for example, in U.S. Pat. No. 5,399,264, employ a relatively rigid, self-supporting, porous, thick-walled tubular filter cartridge element having specially designed flexible end caps. Still other filter cartridges, such as those depicted in U.S. Pat. Nos. 4,218,324 and 5,681,461 employ a "coreless" disposable filter cartridge having rigid preformed end caps which is sleeved over, and fluid-sealed with respect to, a reusable separate core structure. The present invention is related to this latter type of filter cartridge assemblies.
Broadly, the present invention includes a filter cartridge assemblies having a coreless disposable filter cartridge which is sleeved over a reusable separate rigid core structure. More specifically, the preferred filter cartridge assembly of this invention includes a filter cartridge having a generally cylindrical filter medium which defines a cylindrically shaped core space, and a pair of rigid, preformed end caps fixed to opposite ends of the filter medium. Most preferably, the filter cartridge is "coreless" in that it is not provided with an integral support core structure. At least one of the end caps (e.g., the proximal end cap) is annular and has an interior cylindrical surface defining an interior space in alignment with the filter cartridge's core space. A truncated generally conically shaped seal skirt is operatively associated with the annular end cap.
The filter cartridge is sleeved over a reusable support core structure which includes a base having a truncated conically shaped seal skirt, and a tubular perforated rigid core element fixed at one end to the base. The annular end-cap and the base of the support core structure are removably mechanically coupled to one another, most preferably by being threadably interconnected. In such a manner, the seal skirt is sealingly engaged with the seal skirt of the base.
The base of the support core structure most preferably is provided with a protruding seat boss which carries seal rings (e.g., conventional O-rings). The seat boss is thereby adapted to being removably, but sealingly, seated within an internal seat cup structure of a conventional filter housing.
These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the following detailed description of the preferred exemplary embodiments thereof which follow.